There's lots of info on both the Garmin 310XT and 500 on ST but just looking for some direct comparison. From my understanding the 310xt can display power data. The 500 can do this as well. I'm going to be getting into a power meter soon and wondering what head unit to get. I've had a 305 for years and used for running and riding. It would be nice to have a newer unit in the 310xt and also use it on the bike. But, would I be missing anything by using a 310xt with power on the bike? Or are there data fields on the 500 that may be nice to have for power on the bike?

I'd like to keep the price of a head unit around $150. At this point I'm too cheap to get both.

Edit: I'd use the 310xt with the quick release to switch between bike mount and wrist mount.